Iraqi resistance fighters opened fire Monday in Baghdad, killing one American soldier and injuring two others, the U.S. military said. The troops were located at a weapons cache that was discovered the night before.

Elsewhere, Iraqi resistance fighters attacked U.S. occupation forces with mortars in the city of Najaf on Monday. The shelling in Najaf started overnight, when some 20 mortars hit in and around the former Spanish base that U.S. troops moved into a week ago. There were no casualties, The AP reported.

Heavy mortar fire resumed at midday Monday, and U.S. troops returned fire. Troops sealed off the area around the base. Sniper fire could also be heard.

Meanwhile, two Iraqis were killed when they came under fire from US soldiers as they "planted" a roadside bomb in the northern city of Mosul, the US military disclosed.

The device exploded during the shooting, killing the pair, US spokesman Colonel Joseph Piek said Monday.